Newly manufactured automobiles are often shipped over long distances in large numbers aboard specially adapted railroad cars. The railroad cars, typically having two and three decks, are coupled together and loaded or unloaded in long lines.
Loading ramps are then connected at one end of the line with bridge-type ramps connecting the respective decks between cars. The automobiles are subsequently driven aboard the railroad cars, at speeds which often approach twenty miles per hour, and loaded front to back, top to bottom with overhead and bumper-to-bumper clearances rarely exceeding three inches. Ideally, the automobiles arrive at their destination free from defect and ready for sale. As is more often the case, however, they are damaged in transit for a variety of reasons.
Automobiles, like all other freight which is shipped by rail, are subjected to many interactive forces. One such set of forces is caused by slack that is necessarily left when coupling railroad cars to compensate for sags and dips and cresting in the track. These forces, referred to as "buff" and "draft", described respectively the compressive and tensile coupling forces which cause a jerky relative movement between the cars known as "run-in" and "run-out". Another fundamental problem, "rock and roll", occurs because of uneven or rough track, bridges, and grade crossings which set up a resonant rocking condition while the train is in motion. For a detailed discussion of these and other forces, such as yard impacts, which have necessitated various protective measures as described herein below, see TRACK TRAIN DYNAMICS: TO IMPROVE FREIGHT TRAIN PERFORMANCE (2nd Ed.), Report R-185 of the Association of American Railroads, the contents of which is incorporated herein by reference.
One of the earliest methods used to secure an automobile to the deck of a transport, such as a railroad car, was to forcibly restrain each of the automobile's four corners to some means, such as parallel channels, extending along the length of the transport deck. See, for example, U.S. Pat. No. 3,685,856 to Blunden which discloses a vehicle tie-down for haul-away trailers. One major drawback to such methods, nevertheless, was their inability to accommodate varying sizes of automobiles. That is, different makes and styles of automobiles required different lengths of chains and different means for attaching those chains to the automobiles. A more adaptable system was, therefore, desirable. Another problem associated with such methods was the fact that the parallel channels situated along the length of the railroad car deck and to which the tie-down chains are attached form an obstruction to the entry and exit of automobiles. A system which eliminated such channels would, of course, be desirable.
Various improvements to the above-described apparatus, such as those disclosed by U.S. Pat. Nos. 3,564,577 to Blunden et al and 3,866,542 to Blunden, provided carriage means or shoes which were slidably mounted within the channels extending lengthwise of the railroad car, thus yielding some measure of adaptability in securing various sizes of automobiles. Like the simple four-chain method, however, the methods employing such apparatus till subjected the transported automobiles directly to high "G" forces induced by buff and draft, rock and roll, and yard impacts. As a result, automobile manufacturers in order to protect their product had to reinforce the automobile's frame to withstand higher "G" forces than is typically encountered on the highway, and further had to install padeyes, hooks, or other such fixtures upon which the above described apparatus were attached.
In an attempt to alleviate such automobile design problems, it was next proposed to secure the automobile to the transport vehicle by the automobile's tires rather than by its frame, thus advantageously utilizing the automobile's suspension system to absorb the shocks and vibrations of typical railroad operations. One system used straps, either wire cables or woven belts, which would be secured at one end to the transport vehicle deck in front of the tire, lead up and over the top of the tire, and be secured at its other end to the deck of the transport vehicle behind the tire. Such systems, while typically deployed only over the tires along one side of the automobile to preclude having to crawl in an out of the automobile, successfully prevented movement of the automobile in a vertical direction. They were unsuccessful, however, in preventing lateral and longitudinal displacements.
A number of alternative methods were proposed which utilized chocks, both alone and in combination with the straps. Chocks are wedge-shaped apparatus placed immediately in front of and behind a tire to prevent it from moving forward and backward. Chocks used alone were somewhat successful in spite of the often awkward nature of their deployment. Systems which utilized chocks in combination with straps were typically more successful than those using chocks alone, as could be expected. However, in several cases during impact tests simulating railroad car coupling operations, such combination systems either did not prevent the automobile's tires from "climbing" their chocks or were jammed by car movement thus precluding the chock's removal. Moreover, as in each of the above-described prior art methods and apparatus, the chock and strap means which was permanently affixed to the deck of the railroad car, thereby precluding the attainment of an obstruction-free railroad car deck.
The goal of a clear deck was highly preferable from the standpoint of the automobile manufacturers. An obstruction-free deck would not only promote the economically rapid loading and unloading of automobiles onto railroad cars, but also would prevent tire and underbody damage, particularly to the automobile's oil pan and exhaust system.
While directed to a support kit for loading the carrying automobiles as cargo in a standardize, enclosed dry-freight intermodal shipping container, U.S. Pat. No. 4,343,401 to Paulyson discloses a double-decked arrangement which meets some of the above objective. Automobiles are driven onto the upper or track deck and tied down against vertical or longitudinal movement on the tracks by nylon take-up straps extending cross-wise from points of attachment on the bottoms of the automobiles to sidepost mounting tracks. On the container floor, automobiles are secured against longitudinal and lateral movement by specially adapted wheel chocking plates which are mounted as part of the kit to telescoping crossbeams which extend from the conventional sideposts. As can be readily appreciated, however, the Paulyson kit still requires automobile manufacturers to install eyebolts as points of attachment for the nylon take-up straps. Moreover, while requiring no tools for its assembly, the kit is comprised of numerous parts which involve complex and time-consuming assembling. Still further, with the system disclosed by Paulyson, the automobile is restrained by the frame rather than by its tires. As mentioned above, it is desirable to restrain the automobile with its tires because of the additional cushioning provided by the automobile's own suspension system.
One typical approach for freeing up the deck of a transport from obstructions which would be potentially hazardous to automobiles during loading and unloading is disclosed in a German Patent No. DE 31 13707 A1 to Schmidt et al. As disclosed therein, a chock comprised of a triangular frame is hinged to a vehicle loading track such that it may be lifted out of the way for loading and unloading. The frame must still be fitted to the vehicle by bolts, thereby necessitating tools and additional design on the part of the automobile manufacturer.
U.S. Pat. No. 4,659,266 to Thelen et al discloses a wheel chocking assembly in which chocks are mounted on individual frames which are hinged to a track extending along the deck of the loading vehicle so that the chocks may be lifted out of the way for loading and unloading. The frames are movable along the track and the chocks are movable along the frame so that the chocks can be readily moved to position them behind and in front of the wheels of the automobiles. This can be done without the need of any special tools. Thus the chocks can be used for securing a wide variety of automobiles. However, one disadvantage of this chocking system is that it uses a flexible strap secured between the chocks and extending over the automobile tire. The attachment of the flexible strap requires additional handling and the strap is subject to being damaged, either by being worn or cut, during its use. Therefore, it would be desirable to have a chocking system which like the Thelen et al system, provides for a clear deck for loading and unloading automobiles, can be assembled against the wheels of the automobiles quickly and easily without the need of special tools, and can be used with a wide variety of automobiles, but which does not use a flexible strap.